An electric vehicle or hybrid vehicle incorporates not only an electric power storage unit such as a secondary battery unit but also an electric power generator which is driven by a fuel cell or an engine. With such a structure, merely replenishing fuel to the fuel cell or the engine as in a fuel replenishing in a general vehicle allows the electric power generator to be operated with the fuel cell or the engine such that a user is able to preclude a troublesome charging operation for the electric power storage unit per se.
Japanese Patent Application Laid-Open Publication No. H9-222036 discloses an engine control technology to be used in the electric vehicle or the hybrid vehicle which are equipped with the electric power generator and a secondary battery unit. According to such an engine control technology, if a state of charge (SOC) of the secondary battery unit is above a given value and a drive torque command value is less than the maximum torque of a motor, then, the engine is stopped in operation and the motor is driven by electric power output of the secondary battery unit to allow the vehicle to travel.